Novel RNase-based Immunotoxin for CD74-positive B-cell Malignancies

说明(申请人提供)：本申请是对1 R43 CA121468-01的修订申请，最初于2005年7月29日提交。免疫医学公司开发了一系列重组免疫毒素，由两个Rap和一个两栖核糖核酸酶(RNase)分子组成，每个分子都与内化的人源性免疫球蛋白轻链(L)的N端融合。第一个这种免疫毒素，2L-Rap-hLL1-Gamma4P，是通过快速内化的抗CD74人源化抗体hLL1，靶向CD74表达的肿瘤而融合的Rap杀伤肿瘤，并在人Burkitt淋巴瘤异种移植模型中显示出强大的抗肿瘤活性(Chang CH，等)，用一种新型的重组核糖核酸酶/抗CD74人源化IgG4抗体免疫毒素有效地治疗人淋巴瘤移植瘤。布拉德，2005,106：4308-431)。由于2L-Rap-hLL1-Gamma4P中的野生型Rap是糖基化的，2L-Rap-hLL1-Gamma4P的成功促使我们产生了2L-Rap(N69Q)-hLL1-Gamma4P，它包含Rap的非糖基化变体，但在许多属性上与2L-Rap-hLL1-Gamma4P相同，包括所有体外性质的评估、体内肝脏毒性和对携带Daudi淋巴瘤移植瘤的SCID小鼠的抗肿瘤活性。在这一应用中，我们建议进一步开发2L-Rap(N69Q)-hLL1-Gamma4P作为治疗CD74阳性癌症的潜在疗法，特别是多发性骨髓瘤(MM)和非霍奇金淋巴瘤(NHL)。具体地说，我们将评估2L-Rap(N69Q)-hLL1-Gamma4P对携带MM或NHL人肿瘤移植瘤的SCID小鼠的单剂量或多剂量方案的抗肿瘤效果。我们还将通过研究肝毒性是否与免疫毒素的高等电点有关，以及抗炎药是否能有效地减轻这种肝损伤来解决观察到的非特异性肝毒性。另一个目标是扩增生产克隆以增加产量，并使完全扩增的克隆适应无血清条件下的生长。在完成这些研究后，我们应该能够确定2L-Rap-hLL1(N69Q)-Gamma4P在SCID小鼠模型中的治疗窗口，并大规模生产2L-Rap-hLL1(N69Q)-Gamma4P用于食蟹猴的GLP药理学/毒理学研究，以获得支持提交治疗复发或难治性MM或NHL患者的I期临床试验的数据。

DESCRIPTION (provided by applicant): This is an amended application of 1 R43 CA121468-01, which was originally submitted on July 29, 2005. Immunomedics, Inc. has developed a series of recombinant immunotoxins that are composed of two molecules of ranpirnase (Rap), an amphibian ribonuclease (RNase), each fused to the N- terminus of the light (L) chain of an internalizing humanized IgG. The first of such immunotoxins, 2L-Rap-hLL1-gamma4P, was constructed to target CD74-expressing tumors for killing by fused Rap via the rapidly internalizing anti-CD74 humanized antibody hLL1, and has demonstrated potent anti-tumor activity in human Burkitt lymphoma xenograft models (Chang CH, et al., Effective therapy of human lymphoma xenografts with a novel recombinant ribonuclease/anti-CD74 humanized IgG4 antibody immunotoxin. Blood, 2005, 106: 4308-431). Because the wild-type Rap in 2L- Rap- hLL1-gamma4P is glycosylated, the success of 2L- Rap-hLL1-gamma4P prompted us to generate 2L- Rap(N69Q)-hLL1-gamma4P, which contains the non-glycosylated variant of Rap, but is otherwise equivalent to 2L-Rap-hLL1-gamma4P in many attributes, including all in vitro properties evaluated, in vivo liver toxicity, and anti-tumor activity in SCID mice bearing Daudi lymphoma xenografts. In this application, we propose to pursue further preclinical development of 2L-Rap(N69Q)-hLL1-gamma4P as a potential therapeutic for treating CD74-positive cancers, in particular, multiple myeloma (MM) and non-Hodgkin lymphoma (NHL). Specifically, we will evaluate 2L-Rap(N69Q)-hLL1-gamma4P for anti-tumor efficacy in SCID mice bearing MM or NHL human tumor xenografts with a single-dose or multiple-dose regimen. We will also address the observed nonspecific liver toxicity by investigating whether the hepatotoxicity could be related to the high pI of the immunotoxin and examining whether anti- inflammatory agents could be effective in reducing such liver injury. A further goal is to amplify the production clone to increase yields and adapt the fully amplified clone to grow in serum-free conditions. Upon completing these studies, we should be able to define the therapeutic window of 2L-Rap-hLL1 (N69Q)-gamma4P in SCID mice models bearing human NHL or MM xenografts, and produce 2L-Rap-hLL1 (N69Q)-gamma4P in large scale for GLP Pharmacology/Toxicology studies in cynomolgus monkeys to obtain data for supporting the submission of a phase I clinical IND for treating patients with recurrent or refractory MM or NHL.